Input specificity and dependence of spike timing-dependent plasticity on preceding postsynaptic activity at unitary connections between neocortical layer 2/3 pyramidal cells

Cereb Cortex. 2009 Oct;19(10):2308-20. doi: 10.1093/cercor/bhn247. Epub 2009 Feb 4.


Layer 2/3 (L2/3) pyramidal cells receive excitatory afferent input both from neighbouring pyramidal cells and from cortical and subcortical regions. The efficacy of these excitatory synaptic inputs is modulated by spike timing-dependent plasticity (STDP). Here we report that synaptic connections between L2/3 pyramidal cell pairs are located proximal to the soma, at sites overlapping those of excitatory inputs from other cortical layers. Nevertheless, STDP at L2/3 pyramidal to pyramidal cell connections showed fundamental differences from known STDP rules at these neighbouring contacts. Coincident low-frequency pre- and postsynaptic activation evoked only LTD, independent of the order of the pre- and postsynaptic cell firing. This symmetric anti-Hebbian STDP switched to a typical Hebbian learning rule if a postsynaptic action potential train occurred prior to the presynaptic stimulation. Receptor dependence of LTD and LTP induction and their pre- or postsynaptic loci also differed from those at other L2/3 pyramidal cell excitatory inputs. Overall, we demonstrate a novel means to switch between STDP rules dependent on the history of postsynaptic activity. We also highlight differences in STDP at excitatory synapses onto L2/3 pyramidal cells which allow for input specific modulation of synaptic gain.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials / physiology
  • Animals
  • Calcium / metabolism
  • Cerebral Cortex / cytology
  • Cerebral Cortex / metabolism
  • Cerebral Cortex / physiology*
  • Electric Stimulation
  • Excitatory Postsynaptic Potentials / physiology
  • Fluorescent Dyes
  • Long-Term Potentiation / physiology*
  • Long-Term Synaptic Depression / physiology
  • Pyramidal Cells / cytology
  • Pyramidal Cells / metabolism
  • Pyramidal Cells / physiology*
  • Rats
  • Rats, Sprague-Dawley
  • Synapses / metabolism
  • Synapses / physiology*


  • Fluorescent Dyes
  • Calcium